1. Field of the Invention
The invention is directed to the field of wire splicing and more particularly to the joining together of at least two conductors or dead-ending a single conductor without the use of special equipment or tools.
2. Description of the Prior Art
Twist-on connectors are widely used in the electrical industry for splicing solid and or stranded wires in a pigtail fashion. The twist-on connector has an external shell of a suitable non-conductive material such as plastic or rubber of such configuration that it can readily be manipulated. For example, the shell exterior surface may have a series of raised ribs or may include wings or the shell may be formed to have a non-circular external cross-section. A tapered interior passage extends from a large diameter conductor entrance to a small diameter end adjacent the closed shell end portion. Within the shell passage is positioned a spring insert formed of a tapered series of coils of wire complimentary to such passage. Provision is made to lock the final coil of the insert to the shell. In this manner the coil may be expanded to a limited degree to admit conductors within the hollow core of the coil as the connector is twisted-on to the conductors to be joined.
In early twist-on connectors the cross-section of the wire used to form the spring insert was round. As a result the conductors to be joined were contacted by the spring insert along a tangent to such round wire. Insufficient frictional engagement resulted in the separation of the connector from the conductors, allowing the conductors to separate or the joint to be exposed with its attendant dangers.
In an attempt to improve the twist-on connector and prevent unwanted separation of the connector from the wire joint, resort was had to certain non-circular cross-section wire in forming the spring inserts. One of the most commonly employed was the square or rectangular cross-section. When the insert was formed, the wire was positioned such that one of the rectangular corners extended into the coil core so that such corner could engage conductors positioned in said core. However, since it is difficult to form wire with truly sharp edges, the result is a radiused surface which only provides tangential contact with inserted conductors. Similarly, tear drop cross-section wire actually provides only a single tangential contact as well.